This blog has publicized some pretty ludicrous ways of stopping global warming in the past, but today's might really be more than just a gas: Dr. Dieter Adam of New Zealand proposes to do it by genetically engineering "fuel-efficient" cows that don't need to burp very much. According to The Age, this could end up being a $4 million project. The AFP explains:

The project aims to breed more efficient cows that convert their food into more milk and less methane, one of the greenhouse gases blamed for rising temperatures across the planet. ...

In 2003, the New Zealand government attempted to impose a methane tax on farmers because their livestock was responsible for more than half the country's greenhouse gas emissions. But the so-called "fart tax" was dropped after protests from farmers.

We're not talking about an insignificant amount of methane here; Cecil of The Straight Dope says a single cow produces 400 quarts worth of burps every day. Cow poop also releases a lot of methane when it's broken down; some farms have harnessed that power to produce their own electricity. Waste not, want not, I guess.